title: Midbody targeting of the ESCRT machinery by a noncanonical coiled coil in CEP55.
abstract: The ESCRT (endosomal sorting complex required for transport) machinery is required for the scission of membrane necks in processes including the budding of HIV-1 and cytokinesis. An essential step in cytokinesis is recruitment of the ESCRT-I complex and the ESCRT-associated protein ALIX to the midbody (the structure that tethers two daughter cells) by the protein CEP55. Biochemical experiments show that peptides from ALIX and the ESCRT-I subunit TSG101 compete for binding to the ESCRT and ALIX-binding region (EABR) of CEP55. We solved the crystal structure of EABR bound to an ALIX peptide at a resolution of 2.0 angstroms. The structure shows that EABR forms an aberrant dimeric parallel coiled coil. Bulky and charged residues at the interface of the two central heptad repeats create asymmetry and a single binding site for an ALIX or TSG101 peptide. Both ALIX and ESCRT-I are required for cytokinesis, which suggests that multiple CEP55 dimers are required for function.
authors.affiliation: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA.
authors.forename: Hyung Ho
authors.initials: HH
authors.lastname: Lee
authors.forename: Natalie
authors.initials: N
authors.lastname: Elia
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Ghirlando
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lippincott-Schwartz
authors.forename: James H
authors.initials: JH
authors.lastname: Hurley
mesh_terms: D020816:Amino Acid Motifs; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism*; D022082:Cellular Structures / Q000378:metabolism; D018360:Crystallography, X-Ray; D048749:Cytokinesis; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D019281:Dimerization; D056827:Endosomal Sorting Complexes Required for Transport; D011992:Endosomes / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D008954:Models, Biological; D008958:Models, Molecular; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism; D014162:Transfection; D000099177:Tsg101 Protein
chemical_list: D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D009687:Nuclear Proteins; D010446:Peptide Fragments; D014157:Transcription Factors; D000099177:Tsg101 Protein; C505378:Cep55 protein, human; C117020:PDCD6IP protein, human